Adaptive Rake Receiver Joined with Chip Equalization for DS-CDMA UWB Systems over ISI Channels

Abstract

Since there is much larger channel delay spread, there is serious inter-symbol interference (ISI) when ultrawideband (UWB) wireless communication systems work at high data speed. The serious ISI affects the performance of UWB systems seriously. In this paper, a scheme to suppress ISI is developed for direct sequence spread-code division multiple access (DS-CDMA) UWB systems with a high data speed and an adaptive joint chip equalization Rake (AJCE-Rake) receiver is proposed. The proposed AJCE-Rake receiver spreads the number of traditional Rake receiver taps to collect multi-path component and equalize the inter-chip interference simultaneously. Then the soft output of AJCE-Rake receiver is despreaded with the user's spreading code. Finally, the decision is made to recover the transmitted symbol. The simulation results verify that ISI is suppressed effectively and the system performance is improved evidently.